# std::chrono::weekday::ok

From cppreference.com
< cpp‎ | chrono‎ | weekday

constexpr bool ok() const noexcept; |  | (since C++20)

Checks if the weekday value stored in *this is in the valid range, i.e., `[`​0​`,` 6`]`.

### Return value

true if the weekday value stored in *this is in the range `[`​0​`,` 6`]`. Otherwise false.

### Example

Run this code

    #include <chrono>
    #include <iomanip>
    #include <iostream>
    #include <locale>
    #include <string>

    struct weekday_ok : std::numpunct<char>
    {
        std::string do_truename()  const override { return " (is valid weekday)"; }
        std::string do_falsename() const override { return " (is not valid weekday)"; }
    };

    int main()
    {
        std::cout.imbue(std::locale(std::cout.getloc(), new weekday_ok));
        std::cout << std::boolalpha;

        for (const unsigned u : {0 /* Sun */, 1 /* Mon */, 6, 7 /* Sun */, 8, 9})
        {
            const std::chrono::weekday wd{u};
            std::cout << "u: " << u << "; wd: " << wd.c_encoding() << wd.ok() << '\n';
        }
    }

Output:

    u: 0; wd: 0 (is valid weekday)
    u: 1; wd: 1 (is valid weekday)
    u: 6; wd: 6 (is valid weekday)
    u: 7; wd: 0 (is valid weekday)
    u: 8; wd: 8 (is not valid weekday)
    u: 9; wd: 9 (is not valid weekday)

### See also

c_encodingiso_encoding | retrieves the stored weekday value retrieves ISO 8601 weekday value (public member function)

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